Optical pickup device and diffractive elements, optical information device, computer, disc players, car navigation systems, recording devices ON OPTICAL DISCS AND VEHICLE

摘要

FIELD: physics.;SUBSTANCE: optical head device includes a diffraction element which is divided into three regions. Phases of the grating of the left and right hand regions of the diffraction element for generating an additional beam differ from each other by 180 degrees. The central region of the diffraction element for generating an additional beam has a grating structure which differs from the structure of the left and right hand region, and divided into multiple regions to form different gratings which are different from each other.;EFFECT: use of a single diffraction element for discs with different track spacing to obtain a tracking error signal and preventing the fall of the amplitude value of that signal.;36 cl, 24 dwg